Sickle Cell Disease - Block 4 Flashcards
What is the difference betweent SCT and SCD?
SCT: Heterozygous inheritance of one HbA gene and one sickle gene (HbAS)
SCD: Homozygous HbS (HbSS)
What is the cause of SCD?
Gene mutation of b-subunits on hemeglobin (HbS)
What are the classifications of anemia?
Male: Hb <13
Women: Hb <12
Describe the patho of SCD?
- Oxygenated HbS is similar to normal RBC
- Deoxygenated HbS: reduce solubility and increased binding
- Polymeization: distortion of RBC and loss of deformability
- Sickled RBCs: increase viscisty and sludging
- Reoxygenated: polymer lost and return to normal shape
- Cycle: damage to cells, decreased membrane flexibility, and phospholipid rearrangement
- Irreversible sickled cell: decreased flow and increased vascular endothelial adherence
- Intravascular destruction: 10-20 days
How are newborns screened for SCD?
- Isoelectric finding
- High performance liquid chromatography
- Hb electrophoresis
- With + creening have 2nd test before 2 months of age to confirm
When is the onset of SCD in newborns?
4-6 month after birth due to prior presence of HbF (2a, 2y)
* 3-4 months RBC life
Lab findings of SCD in newborns?
- Low Hb (6-9)
- Elevated reticulocytes of 10-25%, platelets and WBC
- Normal MCV
- Sickle cell
Burden of SCD in children?
- Dacylitis before 1 YO
- Hb<7
- Leokocytosis w/o infection
- Rectilocytosis -> stroke and death
- Acute chest syndrome first 3 Y
- SCD + Asthma -> increaed frequency of ACS
Burden of disease in adults?
Decreased survival:
1. chest pain
2. ElevatedWBC
3. CV event
4. Renal failure
5. Proteinuria
6. Pulmonary HTN
What are the goals of SC tx?
Reduce hospitalization, mortality, and complications
Types of health maintenance of SCD?
- Immunization
- Invasive pneumococcal infection prevention
- Renal
- Pulmonary HTN
- Ophthalmological evaluation
- Stroke prevention
How should SCD patients recieve immunization?
Fall under anatomical or functional asplenia due to impair spleen function
How is invasive pnemococcal infection prevented?
Penicillin prophylaxis till 5 YO who pevent with HbSS or HbSb0-thal until they are completely vaccinated against Pneuococcal
* Pen V K+ 125 mg PO BID until 3YO, 250 BID till 5YO
- Erythromycin 20mg/kg/day
How do we screen for pulmonary hypertension?
- Noninvasive tests (Doppler or serum NT-pro-BNP) -> assess mortality
- Pulmonary function test
- Polycomnography
- Oxygenation assessment
- Thromboembolic dx
Indications for Doppler echo?
To screen for PAH and associated cardiac problems by age 8 with frequent cardiorespiratory sx
Recommended Q1-3Y
Tx for SCD-induced PAH?
Cardiac catheterization prior to tx:
Screenign and tx for renal complications from SCD?
Screen: proteinuria by age 10 and annually if negative
Tx: Initiate ACEI for adults with microalbuminuria (30-300) or proteinuria (>300) without apparent cause
Screenign for opthalmological complications from SCD?
Eye exam at 10 YO and rescreen Q1-2Y
Screenign and tx for stroke from SCD children?
Screening: transcranial doppler annually beginning age 2 until 16
Tx: Chronic transfusion therapy for stroke prevention in children with elevated TCD (>200 cm/s)
WHat is the purpose of HbF induction?
Increased HbF -> decreased RBC sickling and adhesion -> Less severe SCD and complications
Examples of HbF inducation tx?
- Hydroxyurea (Droxia, Siklos)
- L-Glutamine (endari)
- Voxelotor (Oxbyrta)
What is the MOA of hydroxyurea?
- Stimulates HbF production, reticulocyted, and intracellular HbF
- Cytotoxic -> stimulates erythropoisis in bone marrow
- Increase NO (vasodilation)
- Decrease RBC adhesion to endothelium
Who qualifies for hydroyurea tx?
Adults with SCD:
1. Three or more sicke cell associated mod-severe pain crises per year
2. SCD interferes with ADLs
3. Hx of severe or recurrent ACS
4. Severe symptomatic chronic anemia that affect ADL
5. Infants (9 months) with SCD
6. CKD on eyrthropien
Hydroxyurea brands or interchangable?
No
Hydroxyurea
DOsing, BBW
Dosing: renal dosing (<60) - 5-10mg/kg
* Admin at the same time everyday
* ANtineoplastic requires proper handeling
BBW bone marrow suppression (leukopenia, neutropenia, thrombocytopenia, anemia, decreased reticulocyte count)
* Reproductive tox
* Carcinogenic
MOA of L-Glutamine
Restores redox balance in oxidative stressed cell by NAD+ synthesis
* reduced pain episodes and hospitalizations
ADR of L-glutamine?
N, C, noncardiac chest pain, fatigue, musculoskeletal pain
Voxelotor
MOA, Indication, DDI, ADR
MOA: HbS polymerization inhibitor -> stabilized the oxygenated Hb state
Indication: ≥12YO
DDI: 1,500 mg taken once daily unless weight is under 40 kg; dose adjustment to 1,000 mg once daily in severe hepatic impairment
* CYP3A4 substrate
ADR: HA, D
What is the function of chronic transfusion?
Purpose: prevent primary and secondary stroke prevention and improve organ damage
Method: simple transfusion, manual and automated exchange
Benefit: increase normal HbA, decrease viscosity, limit volume
Cons: Iron overload, alloimmunization, volume overload, infection, reaction, hyperviscosity
How often are transfusions given?
3-4 weeks but is adjusted to maintain desired HbS levels
What is the transfusion goal?
- HbS concentration <30%
- absence of recurrent stroke for 2 years, Hbs <50%
How do we minimize the risk of transfusion?
- Hep A and B vaccine
- Blood screening (virus)
- Cross matched blood products (phenotyping)
- Avoid excess dietary iron
What is DHTR?
Occurs 7-10 days after transfusion
Sx: hemolysis -> ab pain, anemia, reticulocytopenia
Tx of DHTR?
- Steroids
- IV immunoglobin
- rErythropoietin (reticulocytopenia)
- Rituximab
How do you diagnose transfusional iron overload?
- LFTs and serum ferritin (annual or semi)
- Liver biposy (inflammation or fibrosis)
- MRI
Tx for iron overload?
SC or IV: Deferoxamine
Oral: Deferosirox, Deferiprone
ADR of deferasirox?
BBW: GI hemmorrhage, hepatic injury, AKI
ADR: skin rash, GI
ADR of deferiprone?
BBW: agranulocytosis, neutropenia
ADR: urine discoloration, nausea
Biomarkers for cirrhosis?
- Increased INR, PTT
- Increased biirubin
- Decreased albumin and platelets
Biomarkers for acute hepatic injury?
Increase AST, ALT, ALP
What is the only curative tx for SCD?
Allogenic hematopoietic stem cell transplantation: used prior to organ damage and alloimmunization and screen for HLA identical sibling first year of life
Who qualifies for Allogeneic Hematopoietic Stem Cell Transplantation?
- Children and young adults with sibling matched donors
- For unrelated matched allogeneic HSCT, 16 yo or younger with severe SCD and complications
Complications for Allogeneic Hematopoietic Stem Cell Transplantation?
- GVHD
- Sz
- Marrow rejection
- Sepsis
- Death
What re the presentations of fever?
Fever > 38.5°C (101.3°F) -> determine the risk of infection
Fever ≥ 39.5°C (103.1°F) and ill appearance -> hospitalization
WHat is aplastic crisis?
Decrease in reticulocyte count and rapid development of severe anemia
What is the criteria for hospitalization for fever and infection?
- <1YO
- Hx of previous bacteremia or sepsis
- 103.1°F
- WBB >30
- Platelet <100
Medications for tx fever and infection?
ABX:
* Ceftriaxone/cefotaxime
* Clindamycin (for those with cephalosporin allergy)
* Vancomycin (if acutely ill or Staph suspected)
* Macrolide (Mycoplasma pneumoniae [ACS])
Antipyretics: APAP, IBU
FLuids:
What are vasocclusive processes?
CV occulusion -> stroke and ischemia
What are signs of severe anemia?
- Lower intelligence
- Visual motor impairments
- Neurophysical dysfunctions
Common sign for hemorhagic stroke?
Convulsions
How do we evaluate neuroligc complications for SCD?
Acute: exam (Q2Y), CT, MRI
Screeing: MRI, TCD, EEG
Wht is the tx for neurological problems?
Acute: hospitalization and monitoring
Children: exchange transfusion tomaintain Hgb at 10g/dL and HbS <30%
* Anticonvulsants -> sz
* Tx for increased ICP (mannitol, hypertonic solution)
Adults: Determine if due to SCD or atherosclerotic disease
What is acute schest syndrome?
New pulmonary infiltrate with one or more of the following: cough, dyspnea, tachypnea, chest pain, fever, wheezing, and new-onset hypoxia
How is most at risk for ACS?
Young age
Describe the severity of ACS?
Hypoxia, pulmonary changes (pleural effusions), bilateral infiltrates/multi-lobe involvement
How do we evaluate ACS?
- PE
- CBC
- Chest x-ray
Severe: CT, perfusion scintigraphy, transthoracic echocardiography, bronchoscopy
What is the tx for ACS?
- Incentive spirometry (Q2H)
- Pain managemetn
- Fluid
- Broad spec abx (macorlide or quinolone)
- O2
- Bronchodilator
- Transfusions
- Steroids
- NO
What is the difference between stuttering and ischemic priapism?
Stuttering: repeated intermittant attacks up to several hours before remission
Ischemic: persistent painful erection >4hr (emergency)
What is the non pharm for priapism?
- Exercise, hydration, heat (hot water bottles, hot packs, sitz baths)
- Aspiration
- Surgically placed shunts (severe refractory)
What is the pharm for priapism?
- Analgesic
- Vasoconstrictors to force blood from the corpus cavernosum into venous return (Diluted PE or E)
- Vasodilator to relax smooth muscle of the vasculature (terbutaline and hydralazine)
How can we prevent priapism?
- PE
- Leuprolide
- Hydroxyurea
- Antiandrogen (bicalutamide, finasteride)
What is the location of most SC pain?
Back, chest, extremities
What do we manage acute SCD pain?
Mild-mod: nonopioid +/- weak opioid
Mod-severe: weak opioid or low dose opioid +/- nonopioid
Severe: strong opioid + nonopioid
What are the add on for SCD pain?
- Hydration, O2, heating pads, relaxation, distraction
- Laxatives
- Antihistamine
- Antiemetics
What are the types of analgesics?
Tx for vaso-occlusive crises?
Crizanlizumab (Adakveo)
What is Splenic sequestration?
Sudden massive enlargement of the spleen resulting from the sequestration of sickled RBCs in the splenic parenchyma
How do you evaluate for splenic sequestration?
- Close monitoring of vital signs
- Spleen size
- Oxygen saturation
- CBC
- Reticulocyte count
- Cultures
WHat is the tx for splenic sequestration?
- Fluid resuscitation
- Blood transfusions
- Broad-spectrum antibiotics (if indicated)
- Splenectomy
What is the screening tool for VTE?
D-dimer
What is the diagnosis for PAH?
Pulmonary artery pressure (PAP) > 25 mmHg using doppler
How do we tx PAH in SCD?
- Hydroxyurea
- Chronic transfusion
- PDE5i
How often do you get eye exams?
Anually
How often do you do med evals?
- ≤1YO: every 2-4 months
- ≥ 2YO: every 6-12 months with modifications depending on severity
Tests used for med eval?
- TCD starting 2YOU is HbSS is presnet
- PFTs for patients with recurrent ACS
- Ophthalmologic exam for retinopathy
* 10-12 YOU if HbSC
* 14 for HbSS
How often do you monitor CBC?
< 2YO: every 3-6 months
≥ 2 YO: every 6-12 months
How often do you monitor HbF?
Annually until 2 YO
How are we evaluating in ABX tx?
- Prevention of pneumococcal infection
- Clinical improvement when ill
Tx eval for hydroxyurea?
- Decrease in the number, severity, and duration of sickle cell pain episodes
- HbF concentrations or MCV values
Tx eval for analgesics?
- Patient reported relief
- Non-verbal pain cues ameliorated